Caffeine, one of the world's most popular alkaloids, is found in plants of at least six different families, widely distributed over the globe. Among its varied sources may be mentioned the following plants: coffee, tea, Paraguay tea, guarana from Brazil, cola from West Africa, and chocolate. We shall consider briefly four types of these caffeine beverages—coffee, tea, the caffeinated soft drinks, and lastly chocolate.
Coffee.—The main active ingredient in coffee is caffeine, and it is largely for the effects of this drug that the beverage is used. Roasted coffee contains from .6 per cent to 2 per cent caffeine (averaging about 1.25 percent). A cup made from heaping tablespoonful (about 15 grams), averages Iy4 to 3 grains of caffeine; the latter amount representing the full therapeutic dose of the drug.
As a result of the action of this drug, central nervous system stimulation is marked, resulting in more rapid flow of thought, disappearance of drowsiness and fatigue. Respiration is also increased. However, connected thought and concentration may be more difficult of accomplishment, for impressions may follow one upon the other so rapidly that attention is distracted and confusion results. A common manifestation of this stimulation of the higher nervous centers is insomnia and restlessness, commonly observed in many people following indulgence in coffee or tea at night.
Hawk, in studying the effects of coffee drinking among one hundred young men, observed a definitely unfavorable action in nervous and mental reactions. The coffee drinkers were shown to be less accurate in color selection, in target practice, and in drawing a straight line.' Horst and co-workers reported that both caffeine and coffee taken daily produced a sustained deleterious influence on the performance of acquired motor skills.'
There is a recognized place for such stimulants in therapeutics, as in the emergency treatment of central nervous system depression from narcotics. But the all-too-common practice of indulging in such stimulants as a "pick-me-up" merely to relieve fatigue when rest is needed, constitutes simply a method of borrowing on health reserves. Such a practice, of course, cannot continue without a real price being paid—too often physical bankruptcy. The "pick-me-up" is followed by a "let-me-down," and that not infrequently with a crash.
Increased nervous activity is usually followed by depression, proportional to the degree of the preceding stimulation. That this occurs after caffeine, is indicated by the studies of Horst and his associates, who noted definite depression as late as twenty-four hours after the use of the drug. Those who had the habit frequently complained of nervousness, insomnia, tremors, and especially a morning headache, relieved only by coffee.
That the headache so commonly noted among habitual coffee drinkers is actually a "caffeine-withdrawal headache" is indicated by the studies of R. J. Dreisbach and C. Pfeiffer, who produced "in 55 percent of thirty-eight trials on twenty-two subjects, headache as extreme in severity as the subjects had ever experienced" by the sudden withdrawal of caffeine.' The characteristics of this common headache are gradual onset over a period of a few hours, preceded by lethargy and cerebral fullness. The actual headache, central or occipital in type, usually begins in the early afternoon, later becoming generalized and throbbing, reaching a peak within three to six hours. Associated with this headache are "mental depression, drowsiness, yawning, and disinclination to work."
Other important effects of caffeine include increased circulation as a result of direct heart muscle stimulation, with dilation of the coronary arteries, and increased flow of blood in the skin. Circulatory symptoms commonly noted from excessive use are irregularities in the heart, with palpitation and increased rate; irritation of the stomach, with an increased secretion of acid. From studies of this last-mentioned effect, E. S. Judd reported the production of peptic ulcers in 40 to 50 percent of cats given caffeine in a wax-petrolatum mixture to delay the absorption of the drug.'
Drs. Roth, Ivy, and Atkinson at Northwestern University, produced ulceration of the gastric mucosa of cats by the administration of caffeine in relatively large doses.' These workers also demonstrated a marked stimulation of gastric secretion in man by the use of caffeine, and caffeine-containing beverages. The stimulation produced by coffee was due in part to its caffeine content, and partly to other products, such as the irritant volatile oils.
In patients with peptic ulcer, the secretory response to caffeine beverages was prolonged increase in total gastric acid. Among thirty-six ulcer patients 70 percent reported that coffee aggravated their symptoms.
"Since caffeine and caffeine-containing beverages do not provide a 'buffering effect' but provoke a prolonged secretion of acid in ulcer patients, and since caffeine produces vascular and cellular changes which apparently render the mucosa susceptible to erosion, such beverages should be avoided by the ulcer patient. The evidence indicates that the excessive use of caffeine-containing beverages may contribute to the pathogenesis of peptic ulcer in the ulcer susceptible person, and will render the therapeutic management of the condition more difficult."
In coffee, the volatile oil, caffeol, developed in the roasting process, is the ingredient which gives the beverage its characteristic aroma and flavor. Caffeol is definitely irritant to the gastrointestinal tract, tending to epigastric distress and stimulating peristalsis. It is in part responsible for the gastric irritation and increased secretion previously discussed.
The 12 percent of tannin in roasted coffee is present in the form of "caffeotannic acid." In this form it does not precipitate proteins, and is not astringent.
Decaffeinated coffees (such as Kaffee-Hag, Sanka, etc.), although containing insignificant amounts of caffeine (90 to 97 per cent removed), still contain the irritant caffeol. Bernay and Faure report that this type stimulates gastric secretion in hyperchlorhydria and gastric ulcer about like ordinary coffee.' This observation was confirmed by Roth and associates.'
Tea Tea contains caffeine to the amount of 1.4 to 3.5 per cent, usually about 2 to 3 per cent. The average cup of tea, prepared from a heaping teaspoonful (4 grams) of the leaves, contains about 1.5 to 2 grains of caffeine. (A quick infusion extracts practically all this drug.)
Tannin is usually present in amounts from 4 to II per cent, but is only partly extracted by a quick infusion. By precipitating proteins, lessening absorption, and irritating the gastric mucosa, it is definitely deleterious to digestion.
Cola and other caffeinated soft drinks:
The main constituents of these popular thirst quenchers are sugar and caffeine.
As to sugar, Wilder and Keys in the American Medical Association Handbook of Nutrition state:
"Sugar is not among the recommended foods. . Sugar supplies nothing in nutrition but calories, and the vitamins provided by other foods are sapped by sugar to liberate these calories. One of the worst of the many bad food habits that Americans have acquired is their use of sweetened carbonated beverages. Many persons take such beverages by the half pint many times a day, with a resulting excessive consumption of sugar.""
The Council on Foods and Nutrition makes this important observation: "The consumption of sugar and of other relatively pure carbohydrates has become so great during recent years that it presents a serious obstacle to improved nutrition of the general public." n Ray M. Moose in discussing this states:
"From the Council report it is made clear that when sugar is 'diluting with calories' it is displacing nutritionally superior foods from the dietary, while at the same time it is increasing the requirements of nutrients in the foods displaced. Vitamins Bi, riboflavin, and niacin are necessary for the oxidation of dextrose. Sugar does not supply these vitamins, yet it increases their requirement. When 'diluting with calories,' sugar is thus using vitamins from other foods or from the reserves of body tissues.""
Discussing the habit of taking snacks on drinks containing high carbohydrates during the workday, Wilder, in "Symposium on Nutrition in Industry," sums up the evidence on the subject as follows:
"There may be a nervous element to the production of some of these low blood sugars, but also that tendency to develop low blood sugars between meals is one that may be stimulated, I feel sure, by eating: high carbohydrate meals. It has been shown definitely that if one gives two doses of sugar, one following the other, the elevation of the blood sugar that is produced by the first dose is not observed in the second dose, and that the fall of blood sugar after the dose of sugar is greater after the second dose. . . .
"The objection to giving sugar between meals that way (as in soft drinks) is that one does not provide with it the vitamins that are needed for its own utilization. One throws on the rest of the day's intake of-food the burden of providing those vitamins, and increases the likelihood of the individual's suffering from a chronic or a mild hypovitaminosis. In some cases I think severe grades of hypovitatninosis have been produced by excessive consumption of sugar. Certainly the more of this drinking of soft drinks, between meals or eating rich carbohydrate foods, such as candy bars, at those times of the day when one feels weak and empty, the more likely one is to need to continue to do so, and for that reason, as Dr. Pett said, there is some reason to think that eating sugar instead of correcting fatigue, may lead ultimately to an increased sensitivity to fatigue. I agree with him in that statement.
"We have found clinically at the Mayo clinic, and others have made the same observation, that the best way to treat persons who have this tendency to low blood sugar between meals is to take them off a high carbohydrate diet and put them on a high protein, high fat diet with rather considerable restriction of carbohydrate, and particularly with restriction of-sugar." 13
As to the caffeine content of soft drinks, in Coca-Cola, Roth and others reported a caffeine, content of 33 mg. (about grain) per cup or bottle.' The gastric secretion stimulated by this beverage was 90 per cent of the response to ca., fee.'
The caffeine content of Pepsi-Cola is about tY4 grains (77 mg.) per cup or bottle; and that of Spur is nearly i grain (57 mg.), as recorded by Dr. Roth.
Chocolate and cocoa: Pure chocolate is not pleasant tasting, so before use it is mixed with much sugar and often flavored with vanilla. The chief active ingredient is theobromine, with less caffeine, hence the central nervous system stimulation is not so great. The high fat content (oil of theobroma) tends to disturb digestion by retarding both gastric secretion and motor functions. Acne vulgaris, not uncommon among young adults, may result from the use of chocolate, possibly because of its high fat content.
In an analysis of several brands of cocoa appearing on the American market, the Consumers' Research Bulletin" reported in February, 1946, that in a cup of beverage cocoa as prepared according to directions, there was contained the following: theobromine, .13 to .87 of a grain per cup; caffeine, .09 to .48 of a grain per cup ; tannin 3.75 to 9.76 grains per cup ; fat, ranging from about to to 24 per cent.
It is further suggested in this article:
"Until more is known, however, of the physiological effects of tannin on the digestive system, it is doubtful if one should assume that cocoa is a suitable beverage for very young children." . . . "In the light of present knowledge it would seem wise to regard cocoa and chocolate as flavoring substances to be used sparingly rather than as common items of daily diet."
We are told by Dr. Oliver T. Osborne, professor of therapeutics, Department of Medicine, Yale University:
"There is no question but that a caffeine habit can be acquired, whether as such (Perhaps in the form of Coca-Cola), or as a tea or coffee habit. Coca-Cola, tea, and coffee 'fiends' are of common occurrence. It is not necessary here to discuss the end-effects of the Coca-Cola habit ; it is serious, and especially harmful to children and youth. The cause of the habit is the caffeine in the mixture. It is not pertinent to discuss the small amount that one glass may contain, or that the civilized world drinks tea and coffee freely. The Coca-Cola habit is pernicious."
"Civilized man in this age is over-stimulated and needs something to soothe and quiet him. He (and also she) is beginning to get this quieting from more tobacco than he (or she) ever before used. But if this does not satisfy him, he also, as well as those who do not smoke, will drink more tea and coffee. The result is greater nervous tension, greater nervous irritability, less sleep, more indigestion and finally a lack of mental balance and of physical strength. We are now menaced with the probable over-use of tea and coffee; hence this warning is issued." 17
"The coffee, tea, Coca-Cola, or other caffeine habits may be readily acquired by anyone, and may do as much harm, in some cases, as alcohol and tobacco." 18
REFERENCES
1BAsrEno, W. A. Materia Medica Pharmacology, Therapeutics & Prescription-Writing, 4th ed.; Philadelphia: Saunders, 1938. P. 327.
2 HORST, K., et al. "Effect of Caffeine, Coffee, and Decaffeinated Coffee Upon Blood Pressure, Pulse Rate, and Certain Motor Reactions of Normal Young Men," Journal of Pharmacology and Experimental Therapeutics, 52:325 (1934).
3 Ibid.
4 DREISBACH, R. H., and PFEIFFER, CARL. "Caffeine Withdrawal Headache," Journal of Laboratory and Clinical Medicine, 28:1212 (1943):
5 JUDD, E. S. "Experimental Production of Peptic Ulcers With Caffeine," Bulletin of the American College of Surgeons, 28:46 (1943)
6 ROTH, J. A., IVY, A. C., ATKINSON, A. J. "Caffeine and Peptic Ulcer," Journal of the American Medical Association, 126 :814-820 (1944)•
7 Ibid.
8 Ibid.
9 Ibid.
10 WILDER, RUSSELL M., and KEYS, T. E., in Handbook of Nutrition. Chicago : American Medical Association (1943). P. 283.
11 "Council on Foods and Nutrition," J.A.M.A., 120:763 (1942)
12 MOOSE, R. M. "Sugar, A Diluting Agent," J.A.M.A.„ 125 :738 (1944)
13 WILDER. "Symposium on Nutrition and Industry," J.A.M.A., 121 :869 (1943).
14 ROTH, et al. "Caffeine and Peptic Ulcer," J.A.M.A., T26:814-820 (1944) (citing New Hampshire Health News, vol. 19, July, 1942).
15 ROTH, IVY, ATKINSON. "Caffeine and Peptic Ulcer," J.A.M.A., 126:814-820 (1-944).
16 "Cocoa—For Grown-Ups or Children?" Consumers' Research Bulletin 17: No. 2, 19-23 (February, 1946).
17 OSBORNE, 0. T. Principles of Therapeutics. Philadelphia Saunders, 1922. Pp. 215-216.
18/bid., pp. 603-4.
